Latch



March 13, 1951 w. A. HILGEMAN LATCH Filed Dec. 3, 1945 2 Sheets-Sheet 1FIG. 4

FIG. 3

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HTTOIEA/Eys March 13, 1951 w. A. HlLGrsMAN LATCH 2 Sheets-Sheet 2 FiledDec. 3, 1945 FIG. 5

N .A MMMS TE.Y MG E VM N mim M W L MM Y B Patented Mar. 13, 1951 UNITEDSTATES PATENT oFFIci:

LATCH' Walter-A. Hilgeman, Fairview, I lpl.

Applica-tion December 3, 1945, Serial No. 632,433

(Cl- 29g-11.98)

8 Claimsl This invention relates to. a latch for use in connection withdoorsfin. which a load presses; against. the door putting weightv on thelatch so. that it must be released against the pressure of the load..Morev specifically, it relates to a latch for use on the dipper-.of apower driven shovel. of the type which dumps through the back;

The` conventionalA type of= power driven shovel. has a dipper with adoor in the back for dumping, the door being held` shut by a latch. Theconventional latch in use on all such clippers comprises alatch-loarwhch-` moves in a vertical di. `recton more or less parallelto the back` of the clipper door and onev end: of which is insertedinto. a slot in the dipper 110er-, The dipper is dumped by drawing thelatch toward the top of' the door and out of the. slot. by meansof amotor-powered winch. Since the dipper is dumped through the back, it isapparent that theentire weight of the load rests on the latch when it isin dumping position. Therefore, in order to withdraw the bar, it must bepulled upward against the irictional pressure imposed by the loadfpressing it against the latch-bar slot.

In one broad embodiment, my invention comprises a latch comprising aslotted sill, a latch bolty or bar, means for pivotally mounting the`latch-.bar on a door so as to engage said slotted sill, the pivotpointbeing intermediate the lengthl of said bar, trip. means pivotallymounted on the. door adjacent to but. spaced from the bar, means urgingsaid trip means intoengagement with. one end of said barto prevent itfrom pivoting when in latching position, and means for pivoting the tripmeans toI permit said latch-bar to. pivot.

In another embodiment, the invention com. prises a latch-.bar pivoted.intermediate its length and mountedV for partial pivotal motion on theback of a dipper door, tripping means including a spring engageablewithgone end ofsaidbar to prevent pivoting thereof when in latchingposition, and means associated with said. tripping means to release it:whereby said bar may pivot.

In a. specific. embodiment, `the invention come, prises` ar latch usefulfor example on a power f driven clipper, said latch comprising Valatch-bar ci engageable with a latch-bar-slot associated with `a' sillof clipper, said'bar being pivotal interme. diate its lengthand-pivotally mounted on a dipper A``door, the lower and upperends -otsaidlatch-bar being curved arcuately inwardly toward the dip. per doorto form'bearing surfaces to. aid in the .opening and closing of'thelatch, a. trip, pivotally "mountedion the. dipper door adiaeentsaid.latchbar,said trip comprising a spring retaining mem-N ber,v aspringYurging one end of the trip againstl the latch-bar to prevent pivotalmotion of the latch-har when in latching position, and to re-.. sistreturn of the latch-bar .to latching posi-.1. tion after the latch isreleased,` means to pivot`v said trip to release the latch-bar andpermit it to be pivoted and thereby disengaged from the slot due to theWeightofthe, load within the, dipper.

The device has the advantage that the latch is as firmly held in latchedposition as with the conventional sliding bolt type latch, but that itcan be tripped by the application of a relatively slight pull, since therelease or tripnmechanism does not, have to. overcome the slidingirictional pressure of the loaded latch,l butA merely the pres.- surenecessary to hold the latch bar in position so it cannot pivot. Becauseof the lever prin. ciple used in my invention, the power necessary totrip. the latchl is 1essthantne weight thereof. The conventionallatch-barmay weigh several hundred pounds in thev large machines, andrequires a; substar-i-tial motor tov operate it` My. latch can beoperated with a fractional horsepower motor.

With conventional latches the time lost in re.-,. pairs andi the likemay amount to several hours. a week. This time is largely saved with mylatch.

One difficulty experienced with conventional latches is in plugging ofthe latch-bar slot with rocks or dirt. Oftenthis must be cleared man-Vually, resulting in lost time. Due to the construction of my latch, thelatch bar exerts aV prying action as it enters the slot, thereby clear-4ing it of impediments and saving time. My latch automatically closes andengages when the door slams shut the first time which is not always thecase with the conventional latch. This alsolv is time consuming. Sincethe larger machines,y e.. g. ear-th stripping shovels of 2.0-35 cubicyardsA capacity,-` are rated at several hundred dollars:

per hour, every improvement in efficiency rep-` resents a materialiinancialsaving.

Other advantages will become apparent from the fel-lowing description.

'Ehe inyentienis illustrated. in the. aeeempapreA ins drawings.-

Fsure lillustrates one embodiment of the in: ventien shop/ninperspective and; partly in See: tion from the beek, e.. facing the.@10er-4 Fislire 2; is a plan view of the latch with the protecting capremoved. Figure 3 is a side view partlyv in Section takenthroushlneV'3a-.3 spewing the trip in latehins positilrr! Figures is. e side.vieweine.

ilar to Figure 3 but showing the latch released. Figure 5 is a view fromthe top with the cap in place. Figure 6 is a perspective view partly insection of a detail of the trip mechanism. Figure "I is a detail showingone type of shaft assembly for supporting the latch-bar.

Referring to the drawings, a section of a clipper door of a power drivenshovel is generally indicated at I0. In the conventional type ofclipper, a stiiener II may extend around the edge of the door to preventits buckling under the enormous weights which it must sustain. Thebottom of the dipper is indicated at I2. Associated with the bottom ofthe clipper (the sill) and extending parallel thereto but projectingbeyond the general contour of the bottom is a sill member I3 containinga latch-bar slot I4. The edge of the slot is approximately flush withthe dipper door when it is closed. This is so that when the latch-bar isin position and the door is latched, it will be held firmly in placewithout substantial vibration. The construction of the sill and slot mayvary depending on the device. For example, the slot may be in the sillitself.

Attached to the bottom I2 of the dipper is a stop I5 which isapproximately the width of the latchbar and extends above the bottom ofthe clipper or the sill. The face of the stop is slightly curved toconform to the curved lower face of the-latch bar 28 so as to guide itinto the latching position as the door swings shut. It will be notedthatv this action exerts a prying effect on any material that may stickin the Slot, thereby clearing it' and assuring the latching of theYdoor." The` weight of the door aids in this, while in conventionallatches the only effect is obtained by the weight of the latch-bar. Thisstop may be built u'p approximately the width of the latch-bar and thentapered toward the front of the dipper away from the sill to form abeaver tail which strengthens the stop. An opening I6 is cut in the doorto permit it to pass over the stop I5 and also to permit the latch-barto pivot properly when it is tripped.

Attached to the dipper door I is a pair of support members I'I and I8which contain holes through which shafts I9 and 20 extend. These may beheld in place by means of nuts 2I and 22, and may have square heads 4Iand 44 on the opposite ends. Attached by welding or otherwise to thesupports II and I8 are plates 23 and 24 which serve to support aprotective cover 25 added to prevent dirt from entering the latch. Asmay be seen in Figure l, the plates have a flange 26' extendinginwardly. These are drilled and tapped to take cap screws 21 which holdthe cover plate 25 in position. A latch-bar 28 is pivotally mounted onshaft 20 by means of a hole 29 extending therethrough. This hole may belocated intermediate the length of the latch-bar 28 and is preferablynear the center. The position of the hole will determine to a largeextent the amount of force required to hold the latchbar in position andto release it. The lower end of the latch-bar may have a curved orarcuate end being relieved inwardly adjacent the dipper so as to engagethe curved face of stop i and thus guide the latch-bar into thelatch-bar slot I4 when the door is slammed shut and the latchbar ismoved into the latched position as shown in Figure 3.

The upper end of the latch-bar is likewise curved inwardly but the faceis preferably extended beyond the width of the bar by a projection 30.This projection may serve as a stop by resting against the clipper doorI0 and preventv substantial vibrational movement when the bar is inlatched position. Moreover the face is extended so that the trippingmechanism 3l will have a place to rest when the latch is in trippedposition shown in Figure 4.

When the latch-bar is in latched position as shown in Figure 3, it isheld there by means of a trip 3| which is pivotally mounted on shaft I9by a journal 32. Journalled in the leading or lower edge of trip 3l is aroller 33, which rests against the back face of latch-bar 28 when it isinlatching position (Figure 3) but which rides along the upper curvedface of the latch-bar when it is in tripped position as is shown inFigure 4. This roller preferably has a bearing 34. The shaft I9 isprevented from turning by means of' set screws 35 or other conventionalmeans. The journal 32 for shaft. I9 is located above the upper end oflatch-bar 28; so thatwhen'the trip is released the roller 33 describesan arc beginning outwardly and upwardly over the end of the latch-bar.

There is preferably a slight depression or groove extending laterallyacross the latch-bar 28 near the upper end to aid the roller and tripmechanism to hold latch-bar 28 in latching position.

Attached to the trip 3l near the forward face Tis a'link 36 whichextends approximately parallel to the door and out through a hole 31 ,inthe cover 25. A flexible bellows,A not shown, may y seal this hole.A Alink orloop is placed in the end-l of link 35 for attaching -cable 38.Vwhich runs tof, atrip mechanism which is 'mechanically pow-g ered in thecase of power driven shovels. yByfJ pulling upward on cable 38 theleading or for-5"V ward edge of the trip mechanism 3`I is caused topivot upwardly and outwardly disengaging itself from the vertical faceof latch-bar 28 and thus permitting the weight of the load on theclipperdoor to thrust the door outwardly into the position shown inFigure 4. Y Y

A spring retaining member such as arm 33 extends from the trip mechanismat a point remote from roller 33. That is, the pivot point lies betweenthe arm 38 and the roller 33 so that movement of either exerts anopposite effect on the other member. A spring 4B urges the arm away fromthe dipper door. Thus, referring to. Figure 3, when the latch is inlatched position the spring urges roller 33 against the back face` oflatch-bar 28 Aand prevents it from pivoting around point 29. The tripmechanism is operated Vby momentarily raising the leading edge of theitrip including roller 33, thereby permitting latch, bar 28 to pivot dueto the weight pressing against the door. As it pivots, roller 33 ridesup and over the end of bar 28 and the lower end of Vbar 28 rides free oflatch-bar slot I4 and the dipper door is free to open. -The action indisengaging the latch-bar from the slot is, in effect, a rolling motionrather than a sliding motion as in the conventional latches.' The slot.I6 in. the door prevents more than limited' pivoting of the latch-bar,the lower end of which must clear the sill.

The roller 33 nowgis pressed against the curved' face of the upper endof bar 28 so that; the bar ,isprevented fromv dropping back intolatching position and so that the lower end will be held in a positionto clear the: sill when the door subsequently swings shut; This isessential to the successful operation of the latch.

Spring Y 40 is held in ,place by conventional.. means shown asprojections 45 and 46 on the door-and arm 39 respectively. The spring iscomparativelywea-k sinceV it need only bestrong enoughY toovercomethe-tendency of arm 28 to pivot.

Refer-ringto Figure 7, this'is aV detail of one.

means ofA associating shaft 2U with the mechanism. A square head 4I isattached to the shaftfwhichis driven through a hole in support I 8.` Theshaft is prevented from turning by meansV ofalug 42. The opposite end ofshaft 2B is threaded to receivewasher 43 andi nut 22. The latch-bar 2Sforms a journal for this shaft andthe-latchebarpivots-around the shaft.Preferably the latch bar is of hard steel so that most of the wearoccurs-onsha-ft 20. When the shaft becomes-worn, anew bearing surfacecan bepresented by merely withdrawingr the shaft and turning it a,.quar.ter turn. Thusthe bearing surface can be renewed three timesbefore a new shaft must be supplied. Shafts I9 and 20 are preferablyidentical. An alternative structure of the latch-bar provides that theshaft 2Q. may beV made integral with` latch-bar and bearing provided, e.g. pillow bearings, to provide pivot means for the bar. As illustrated,provision is made for lubricating the pivotable bearing by means of acounter sunk grease fitting and a hole drilled through the shaft andopenings within the bearing.

A shield or cover E' over opening I6, may be provided to protect the;latch-bar, 28 from damage and dirt. There is an opening below the cover25 to allow any dirt that gets into the mechanism to work free. Whenassociated with the dipper of a power driven shovel, the mechanismoperates in the following manner.

As shown in Figure 3 the latch-bar 2B is approximately parallel to thedipper door. The lower end of the latch-bar is associated with thelatch-bar slot I4 and thus prevents the dipper door from opening. Thespring 40 thrusts against arm 39 thus urging the roller 33 against thelatch-bar 28. 36 or cable 38.

When the dipper is raised into position to be dumped, tension is appliedto cable 38 usually by means of a motor which drives a suitable cabledrum. Only a momentary pull is required and this may be usually donewith a fractional horsepower motor since it is only necessary toovercome the action of spring li in order to release the trip. Once thetrip mechanism begins its outward and upward movement, the weight of theload pressing against the door causes latch-bar 28 to pivot around point29 and move into the position shown in Figure 4. The motion is a rollingmotion, not sliding, and the force necessary is provided by the weightof the load, notthe tripping mechanism. rIhe roller 33 rides along thecurved surface of the upper end of the latch-bar 2t. The latch-bar isprevented from moving more than a limited distance since it strikes theupper part of slot I e in the door. The trip motor operates onlymomentarily and immediately releases tension on cable 38 so that. thespring di) again exerts its pressure. It thrusts roller 33 against theinwardly curved surface of bar 28 and prevents it from moving of its ownweight, back into latch position. Thus bar 2B is held so that the lowerend will clear the sill as the door subsequently swings shut which itwould not do if the latch-bar could assume a position parallel to thedoor before the lower end cleared the sill. Any suitable retainingmember may be employed to limit the pivot of the latch- No tension isapplied to link 6. bar-l andA the door may-be reen-forced at the pointwhere the bar strikes.

When the dipper is lowered, the door swings-` shut-'because of its-ownweight, bringing the lowercurved-surface-,of latch-bar 28 into` contactwith thecurvedsur-face of the-stop l5. As-theweight continues to pressagainst the latch-fbar, it is guideddownwardly causing it to pivotatpoint 29. Since the strengthvof: the spring is too small to: resistther weight of the door, the roller 33 rides along the upper curvedkface of the latch-bar; and over the projecting pointr until it assumesthe position shown in Figure 3 where it prevents further pivotal actionof the latch-bar-untilit l is-releasedby'a pullon cable 38.

Conventional types of oilers may be applied. A hole-lli isprovided inplate 23 to reach an oiling mechanism in the-end of shaft I 9.

It should be understood that this inventionis not limited to theexacbforms shown orA described. v i

I claim as my invention:

1. A latchruseful on power driven dippers'which comprises spacedsupporting members attach-` able to a door, a shaftr through two of saidsupporting-members, a latch-bar pivotallymounted on; said shaftintermediate the length ofthe bar, saidy bar being relieved arcuately ateach end inwardlyV toward thev door,y the lower end-'of said bar beingengageable with a` slotted sill member, a shaft mounted on two of saidsupporting mem-y bers, a trip member mounted pivotally on the shaft, aroller associated with one end of said trip member and engageable withthe back of said latch-bar when it is in latching position, an armextending beyond the pivot point of said trip member, a spring normallyurging said arm away from the door so as to engage said roller with theend of said bar, and means for urging said arm toward the door therebyovercoming the eect of said spring and moving the roller away from saidbar thereby permitting the bar to pivot.

2. A latch for doors carrying weight against the latch when the door isto be opened, comprising a latching device attachable to the door, saiddevice comprising a pair of spaced shaft supports, shafts extendingtherethrough, a latchbar pivotallymounted on one of said shaftsintermediate the length of said bar, said bar being adapted to engage asill member of the door, a trip member pivotally mounted on the othershaft, said trip member comprising a roller engageable with saidlatch-bar to prevent pivoting thereof when in latching position, andtending to urge the latch-bar out of latching position when innon-latching position.

3. A latch comprising, a latch-bar support, a latch-bar pivotallymounted on the support at a point intermediate the length of the bar, atrip support, a trip pivotally mounted thereon adjacent but spaced fromone end of said bar and engageable therewith to prevent pivoting of thebar when it is in latching position, the opposite end of the bar adaptedto engage a cooperating latch keeper, means normally urging said tripagainst said bar and means to which force may be applied to oppose theaction of the last named means, thereby removing the retaining effect ofthe trip on said bar and permitting pivoting of said bar.

4. A latch comprising, a latch-bar support, a latch-bar pivotallymounted on the support at a point intermediate the length of the bar, a

trip support, a trip pivotally mountedthereon adjacent but spaced fromone end of said bar andV engageable therewith to prevent pivoting of thebar when it is in latching position, the opposite end of the bar adaptedto engage a cooperating latch keeper, means normally urging said tripagainst said bar and means to which force may be applied to oppose theaction of the last named means thereby removing the retaining effect ofthe trip on said bar and permitting pivoting of said bar, and a covermountable over said latch-bar and said trip, said cover having anopening for said force applying means and an opening for the latch-bar.

5. A door latch for doors subjected to heavy door opening pressure, saidlatch tending to unlatch under the iniiuence of said pressure whenreleased, said latch comprising a support adapted to be mounted on adoor; a latch bar pivotally mountedon said support intermediate thelength of the bar, the forward end of said bar being adapted toselectively engage or disengage a cooperating latch keeper when the baris pivotally rotated in one direction or the other; a trip memberadapted to engage a surface on the rear end of the bar when in latchingposition thereby preventing rotation of the bar, said trip member alsoadapted to engage another surface of the rear end of the bar to urge thebar out of latching position when the bar is in non-latching position;means for impelling the trip member into engaging position with the bar,control means to actuate the trip member out of engaging position atVwill against the influence of the impellingl means thereby permittingthe bar to rotate under the influence of a pressure against the door.

6. The latch of claim 5 characterized by the fact that the rear end ofthe bar comprises a cam surface and the trip member comprises a rolleradapted to be engaged therewith.

'7. The latch of claim 5 wherein the latch bar is substantially straightand centrally pivoted.

8. The latch according to claim 5 wherein the impelling means is aspring.

WALTER A. HILGEMAN.

REFERENCES CITED The following references are of record in the le ofthis patent:

` UNITED STATES PATENTS Number Name Date 383,886 Jackson June 5, 1888829,825 Alexander Aug. 28, 1906 971,423 Walters Sept. 27, 1910 982,087OConnor Jan. 17, 1911 1,725,858 Esters et al Aug. 27, 1929 2,095,322Elmes Oct. 12, 1937 2,339,073 Hobson et al. Jan. 11, 1944 FOREIGNPATENTS Number Country Date 155,050 Great Britain Dec. 16. 1920.

